Grade-crossing signal



March 1931- H. N. BRANDALL 1,797,974

GRADE CROSSTNG SIGNAL Filed Aug. 15. 1928 5 shee rfsqheet' 1 l' GUM/Mud,

March 1931- H. N. B RANDALL 1,797,974

GRADE CROSSTNG SYGNAI:

Filed Aug. 15. 1928 5 Sheets-Swami 2 7 H/VT Bran/Jazz.

March 1931- H. N. BRANDALL GRADE CROSSING SIGNAL Filed Aug. 15, 1928 5Sheets-Sheet 3 1? mzrandazz.

March 24, 1931. H. N. BRANDALL ,9

GRADE CROS S ING S IGNAL Filed Aug. 15, 1928 5 Sheets-Sheet 4 4f 40 HJVIZfanaa/ZZ.

March 24, 1931. BRANDALL 1,797,974

GRADE CROSSING STGNAT.

Filed Aug. 15, 1928 5 Sheets-Sheet 5 imme/MM H. NBranJa/Z Patented Mar.24, 1931 UNITED STATES HARRY N. BRANDALL, OF FAIRFIELD, IOWAGRADE-CROSSING SIGNAL Application filed August 15, 1928. Serial No.299,793.

This invention is a signal mechanism intended particularly for use atgrade crossings and to be operated by an approaching train to notifyusers of a road that a train is about to reach the crossing. Aparticular object of the invention is to provide an apparatus which willcause a signal to be given only while the train is approaching thecrossing so that pedestrians and the occupants of vehicles upon a roadwhich intersects a railway will not be misled by false alarms and,consequently, induced to ignore a signal, when given, by reason ofhaving been misinformed by the improper operation of signals. An- 16other object of the invention is to provide means whereby, when thesignal is applied to a single track road, the alarm will be given onlywhen a train is approaching the crossing and will be inoperative whenthe train is passing or has left the crossing. Another object of theinvention is to provide a signal mechanism which will operate thesignals through a predetermined period. Other objects of the inventionwill appear in the course of the following description, and theinvention resides in certain novel features which will be particularlypointed out in the appended claims.

In the accompanying drawings which illustrate the invention Figures 1, 2and 3 are sectional elevations of one embodiment of the invention,showing the actuating mechanism in different positions assumed as carwheels are passing thereover in one or the other direction;

Fig. 4 is a vertical transverse section on the line 44 of Fig. 2;

Fig. 5 is a top plan view with the cover of the casing removed;

6 is a detail plan view, partly broken away and in section, of theoscillatory container in which circuit-closing elements are mounted;

Fig. 7 is a detail perspective view of a trigger which forms a part ofthe operating mechanism;

8 to 12 inclusive are longitudinal sections through the oscillatorycontainer showing the same in different positions and illustrating theoperation of the circuit-closing .5 elements;

Fig. 13 is a diagram of the apparatus applied to a grade crossing;

Figs. 14, 15 and 16 are views similar to Figs. 1, 2 and 3 but showinganother form of the invention;

Figs. 17 and 18 are longitudinal sections of the container shown inFigs. 14, 15 and 16, illustrating different positions assumed by it inoperation; I

Fig. 19 is a section on the line 19-19 of Fig. 17, and

Fig. 20 is a detail section on the line 20-20 of Fig. 14.

-In carrying out the invention, there is secured to the side of a trackrail 1 a casing 2 in which the circuit-controlling elements are mounted.This casing is secured to the web of the track rail by bolts 3 insertedthrough bosses at the corners of the casing and through the web of therail, as will be understood upon reference to F i s. 1 to 4. The casmgmay be constructed 0 any suitable material, preferably sheet metal, andis formed with a longitudinal vertical partition 4 whereby it is dividedinto an outer trigger chamber and an inner circuitclosing chamher, and acover 5 is fitted over the casing so as to entirely close the same andprotect the interior of the same from the action of the weather andprevent the operation being clogged or hindered by moisture or anaccumulation of dirt or other foreign matter, the cover beingconstructed with transverse slots 6 to accommodate the working ends oftriggers which are mounted within the trigger chamber and intended to beactuated by the wheels of passing cars. Pivotally mounted upon the upperbolts 3 are resilient trip levers-7 which extend over the cover from theopposite ends thereof and are formed of spring-tempered metal havingsufficient strength to normally occupy the positions shown in Fig. 1 andresist depressing action exerted thereon by any weight less than thatimposed through the car wheels, a portion of one of the car wheels beingshown at 8. It will be noted that these trip levers are provided attheir outer edges with longitudinally extending depending lips orflanges 9 which are disposed at the outer side of the casing and thatthe trip levers are of such width that they will extend to thelongitudinal shoulder or ridge in the cover and thereby serve to preventthe entrance of moisture or other matter through the slots 6 in thecover. Pivotally mounted within the upper portion of the trigger chamberof the casing, between the center of the same and the respective endsthereof, are triggers 11 and 12 each of which consists of a pendent bodyand an angular arm 13 projecting laterally from one side of the body atthe upper extremity thereof and terminating in a finger 1a which isadapted to project upwardly through the respectively adjacent slot 6 andbear against the under side of the respective trip lever 7. The weightof the body of each trigger is obviously greater than the weight of thearm and its terminal finger so that normally the triggers will assumethe positions shown in Fig. 1 with the bodies vertical or substantiallyvertical and the trip levers extending obliquely inward over the coverof the casing and out of contact therewith. Pivoted to the trigger 11,

near the lower end thereof, is a pull bar 15 formed in its under sidewith a notch or re cess 17 having a vertical shoulder 18 at one end andhaving its opposite end beveled or inclined, as indicated at 19. Mountedin any convenient or suitable manner in the lower portion of the casingat the center of the same is a rock shaft 20 and secured upon this rockshaft within the trigger chamber is a forked lever or crank 21 throughthe upper forked portion of which the pull bar passes, as shown clearlyin Figs. 1 to 4. When the mechanism is at rest, as shown in Fig. 1, thepull bar rests upon the lever 21 between'the tines 22 of the same withits vertical shoulder 18 engaging the edge of the lever between thelower ends of the tines. By referring particularly to F igs; 1, 2 and 8,it will be seen that the device is intended to be operated by a traintraveling from right to left in the drawings in whichevent the car wheel8 will impinge against the right hand trip lever 7 and depress the sameso as to rock the trigger 11, as shown in Fig. 2, and thereby draw uponthe pull bar 15 so that the crank or lever 21 will be rocked toward theright; If the train approaches from the left, the wheel impinging uponthe left hand trip lever 7 will depress the same and rock the trigger 12toward the right and, a a result of this action,'the pull bar will belifted about its pivotal connection,

with the trigger 11 so that it will be disengaged from the crank orlever 21, and when the car wheel subsequently depresses the right handtrip lever and rocks the trigger 11, the pull bar will bev merely drawnthrough the crank or lever 21' without actuating the same, as will beunderstood upon reference to Fig. 3.

As shown in Fig. 4c, the rock shaft 20 extends entirely across thecasing, and within the circuit-closing chamber there is secured to theshaft a container 23 of insulating material which is substantiallytriangular in side view. This container is constructed with a centralpartition 24 radial to the rock shaft and having a large opening 25there through adjacent its lower end, and constructed in or near itslower edge with a central notch or passage 26 of very restricted areawhich constitutes a percolating orifice to permit a retarded return flowof the mobile circuit-closing element from the right hand chamber of thecontainer to the left hand chamber thereof. Secured in any convenientmanner upon the right hand side of the partition 241- in position tocover the opening 25 therethrough is a check valve 27, shown in Fig.4and Figs. 8 to 12, in the form of a flap of leather or other flexiblematerial which is secured at its lower edge below the port and has itsupper portion free to move toward and from the partition. Mounted in thetop of the container at the right of the partition areconductorterminals 28 and 29, these terminals being of like formationand the terminal 28 being shorter than the terminal 29. A body ofmercury, indicated at 30, is placed within the container and is adaptedto bridge the terminals 28 and 29 so as to complete an electric circuittherethrough, but normally, as shown in Fig. 8, the level of the mercuryisbelow the end of the terminal 28 so that the circuit will be brokenand the signal. will be inoperative. When the container is rocked, thebody of mercury will be shifted so that its level will rise invcomparison with the terminals and the circuit will be closed between theterminals 28 and 29 and will remain closed until the mercury, throughits inherent action in seeking to return to a level, recedes below theshorter terminal and breaks the circuit. Obviously, the signal will besounded through an interval which may be predetermined and, in actualpractice, the terminals will be fixed in the top of the container andthe relative lengths thereof will be such that the signal will besounded through such an interval as experience has shown to bedesirable. In the drawings, however, I have shown the shorter terminal28 as provided with threads 31 along its upper portions so that inassembling the device the terminal may be adjusted as desired, theterminal passing through a nut 32 embedded in the body of the containerand having its upper extremity constructed to be engaged by screw driveror other similar tool.

In order to avoid oxidization which is apt to.

occur through contact of mercury with other metals, a thin film ofglycerine, indicated at 38, 1s deposited upon the top of the mercury Iboiio

and this film, being lighter than the mercury, will always be 011 topthereof notwithstanding variations in the level of the mobile body andit will not only resist oxidization but will also serve to cleanse anysurface upon which oxidizing effects may appear.

Conductors 34 are embedded in the walls of the container and eachconductor has its end secured to one terminal. One of the conductorsextends to one side of a battery or other source of current, indicatedat 35, Fig. 13, while the other conductor extends to one side of thesignal, indicated at 36, and this signal may be a hell or a lamp or anyother approved form of audible or visual alarm, one side of the signalbeing connected to the corresponding side of the battery by a conductor37. It will now be obvious that, when the terminals 28 and 29 areelectrically connected, the circuit will be closed through the signaland the battery and the signal operated. It will also be understood thatthe car wheels and axles do not form part of the circuit although itmaybe convenient at times to utilize the track rails as portions of theconductors 34.

Referring now more particularly to Figs. 8 to 12, it will be noted thatin the normal posi tion of the container shown in Figs. 1, 3 and 8, thelevel of the mercury will be below the terminal 28 with the greater bodyof the mercury in the lower portion of the left hand chamber in thecontainer, although a small quantity of the mercury will be in thebottom of the right hand chamber owing to the presence of the minuteorifice 26 in the lower end of the partition 24. Assuming the trigger 11to be actuated by a car wheel approaching from the proper direction, asindicated in Fig. 2, the container will swing toward the rightwith therock shaft 20, and the initial move ment will cause the mercury to bankagainst the partition 24, as shown in Fig. 9. The weight of the mercurywill be thrown against the check valve 27 and will open said valve sothat the mercury will rush through the port 25 into the right handchamber of the container, the level of the mercury dropping in the lefthand chamber. When the mercury surges into the right hand chamber of thecontainer, it will momentarily close the circuit through the terminals28 and 29 and cause a very short initial operation of the signal but itimmediately subsides and breaks the circuit, the shape of the outer wallof the chamber and the volume of the mercury being such that the surfaceof the mercury will be below the terminal 28 as long as the container isin any of the positions shown in Figs. 8, and 10. As the container makesits return movement, the weight of the mercury will act in the oppositedirection upon the check valve and will close the valve, as shown inFig. 11, so that the mercury will be banked about the terminals 28 and29 and will maintain the circuit closed for such period as is requiredto permit it to return to the left hand chamber through the percolatingport or orifice 26. The rocking movement of the container is certain andis rather sharp, an expansion spring 38 being provided to receive theimpact of the container upon its movement to the right and immediatelyexpand and start the return movement thereof, and to cushion the returnmovement a buffer 39 of rubber or other suitable material is provided inthe casing, as shown in Figs. 1, 2 and 3. The triggers 11 and 12 beingoverbalanced so that they tend to remain in the vertical pendentposition shown in Fig. 1, the trigger 11 will return to normalimmediately after the car Wheel has cleared the trip lever 7 actingthereon, the pull bar riding through the forked lever 21 and through theopening 16 in the trigger 12 so that the crank 21 will then be free torock with the container and will not retard nor arrest the movementthereof but will ride under the pull bar which will drop by its ownweight into the position shown in 1 when the parts have 7 assumed theirinitial positions. The strength of the spring 38 is not so great that itwould prevent the container moving the full distance to the right but itis strong enough to start the return movement and move the container tothe position shown in Fig. 11. At this time the mercury will be banked.high in the right hand chamber of the container and bearing against thepartition but will. be percolating through the orifice 26 into the lefthand chamber and, consequently, the weight of the mercury will tend tocontinue the return move ment of the container, but the circuit isclosed and the signal is operating. Eventually, the

flow through the orifice 26 into the left hand chamber will bring thelevel of the mercury below the terminal 28 and thereby break thecircuit, whereupon the operation of the signal will cease. The triggersand the container will have returned to initial position.

It will be understood that the signal-closj in g container and the partscooperating therewith will be located. several hundred feet from thecrossing so that any one who may be crossing when the signal is operatedwill have an opportunity to leave the track before the train reaches thecrossing. The apparatus which has been described is intended for use onsingle track roads but it may be applied to double track roads and whenso applied the only thing that needs to be done is to remove the lefthand trigger 12. Crossing signals, as heretofore constructed, have beenoperated by the closing of a circuit through the car wheels and thetrack and, consequently, the signal was sounded whenever the train wasin the signal block, whether the train was in motion or at rest. In myapparatus, the signal is closed by the passing car wheel but does notextend through the Wheel and is ..i

. adapted for use upon side tracks where motionless cars make the use ofother signaling systems impossible but where there is great danger fromthe switching of cars at unguarded crossings. The casing or my device ispractically watertight and the oscillatory container is absolutelywater-tight so that the action of the air or the weather will have noeffect upon the operation of the device. The device will, of course, beactuated by each wheel of the passing train and will operate for apredetermined period after the last wheel has passed, but if a wheelshould come to rest over the trigger 11the container will not make itsreturn movement but will he held in a position determined by the depthof depression of the trigger, and the signal will not operate becausethe level of the mercury will be below the terminal 28. Due to thisfact, the circuit is broken as each wheel passes but closes instantly asthe container returns to normal. A false alarm, therefore, cannot begiven. It will be noted that the signal has an intermittent action,being operated for a very short interval, a preliminary warning or flashbeing thus given, followed immediately by cessation of the signal andthen a longerperiod of operation as the mercuryslowly recedes from thecircuit terminals. A very rapidly moving train, therefore, would'causethe signal to operate at frequent intervals which, in some instances,would be practically continuous owing the very short periods of brokencircuit while a slowly moving train would cause greater interruption tothe signal activity because the trigger would'be depressed tor thelonger period of time a car wheel was over it.

The embodiment of the invention which has been described is preferredfor installation where an irregular flashing of a light is permitted, orit is not requiredthat a light flash a given number of times in a statedperiod. The latter type of signal requires a continuous current up tothe signal and the flashing is controlled by electrical mecha nism at ornear the signal. To meet this condition, I provide the structure shownin 14 to 20 in which a longer closed work ing condition of the circuitis attained.

The casing 40 is secured to the side of a track rail by bolts 41 and atthe upper con ncrs thereof are mounted trip levers 42, 43.,corresponding in all respects to the trip levers 7 of Figs. 1 to 4, thetop of the casing having openings therethrough tor the ac coinlnodationof hearing, at their upper ends, against the respective trip levers, asshown. The trigger 4 is pivotally mounted, as at 46, and is offset orbent in the region of its pivot so that the t ers 44 and its upperextremity is disposed between its pivot and the adjacent end of thecasing, but

the trigger 45 is straight and has its lower end seated in an expansionspring 47 whereby it is held to the trip lever .43, said trigger 45being readily reciprocable vertically but having practically nooscillatory movement. In the lower end portion of the trigger 45 anopening 48 is formed there through to receive and slidably support thefree end or" a pull bar 49 which is pivoted at or near its opposite endto the lower end of the trigger 44, and a retractile' spring 50'isprovided between the trigger 44 and the. adjacent end ofthe casing tonormally hold the parts in the positions shown in full lines in Fig. 14.Fixed to the pull bar, between the triggers, is an upstanding bracket 51having its upper extremity turned, toward the Assuming a car toapproachfrom the left,"

as indicated in Fig. '14, the trip lever 42 will be depressed and thetrigger 44 thereby rocked, asshown by the dotted lines, the pull barsliding through the trigger 45 and also swinging upwardly. The dog53.will be carried against and past the cam 55 and will rock upon itsown pivot to clear the cam, dropping into normal position against thebracket 51 as soon as it is free of the cam so that, upon returnmovement, it will be in position to engage the shoulder 56 and actuatethe cam and rock shaft. As the car wheel, however, leaves the trip lever42, it at once passes onto and depresses the trip lever 43 so that thetrigger 45 is pushed down and the free end of the pull bar likewisemoved downward to carry the dog-to a position below the cam.Consequently, the return movementof the pull bar and dog, which iscaused by contraction of the spring 50 and occurs while the trigger 45is depressed, will have no e'fiect on the rock shaft and the signal willnot be operated. When a car approaches from the right, the wheel willdepress the trip lever 43 and the trigger 45 which will resume theirraised positions as the'wheel passes from the trip lever. As the wheelleaves the trip lever 43, it passes onto and depresses the trip lever 42and thereby, in the'manner before described, swings the dog into theposition shown in dotted lines in Fig. 14 and full lines inFig. 15. Whenthe dog now makes its return movement as the wheel leaves the trip lever42, the cam will be engaged and rocked inasmuch as the trigger remainsin its raised position, as will e understood on reference to Fig. 16.

An oscillatory container 57 is fixed upon the rock shaft and issubstantially triangular in side view but is relatively longer than thecontainer 23 first described and its apex is at its top instead of thebottom. A transverse partition 58 divides the container into twochambers, and it may be here noted that the partition may be integralwith the body of the container or formed separately tached thereto andthe body may he produced in parts to be subsequently united asnecessities of manufacturing may dictate but all joints must behermetically sealed. At 59 I have indicated a plugged and sealed openingthrough which mercury 60, was placed in the container and at 61 isindicated a weight upon the more attenuated end of the container toassist the mercury in holding the container in normal position shown inFigs. 14 and 15 and returning it slowly to said position. The partitionis formed with a relatively large port 62 and a very small orifice 63below said port. Flow through the port 62 is controlled by a check valve64 in the form of a very thin flexible tube having one end sealed aroundthe port and its opposite end free in the right hand chamber of thecontainer. When the container is rocked to the position shown in Figs.16 and 18, the mercury rushes through the tube but the free end of thetube will float with the rising level of the mercury and, when the flowceases, will close under the surrounding pressure. Terminals 65 areprovided in the right hand chamber of the container and are constructedin the same manner as the terminals 29 but are located adjacent the endwall of the container and are disposed at a greater angle to thepartition so that submersion in the mercury will continue through alonger period and there will be less frequent breaking of the circuit.As long as the left hand end of the container remains elevated, the camwill be out of the range of the operating dog and as it slowly returnsto normal the cam will be engaged in propor tion so that the right handchamber will be kept filled with mercury with a minimum operation of thecontainer.

My apparatus may be installed at a low cost and Will practically costnothing to maintain so that it may be employed in all places wherecrossings are now left unguarded because of the prohibitive cost ofpresent signals. The resilient trip levers absorb the shock due toimpact from the car wheels and also serve as shields for the triggermechanism against rain, snow and ice and safeguards it from malicious oraccidental tampering.

Having thus described the invention, I claim:

1. An apparatus for the purpose set forth comprising an oscillatorycontainer, means within the container for intermittently closing anelectric circuit through a predetermined interval, a rock shaft carryingthe container, a trigger mounted in proximity to the container tooscillate in a vertical plane parallel with the side of the container,means whereby said trigger may be actuated by a passing car wheel, andmeans operatively connected with the lower end of the trigger for attimes rocking the shaft and the container.

An apparatus for the purpose set forth comprising an oscillatorycontainer, means within the container for intermittently closing anelectric circuit through a predetermined interval, a rock shaft carryingthe container, a trigger mounted in proximity to the container, meanswhereby said trigger may be actuated by a passing car wheel, meansoperatively connected with the trigger for rocking the shaft and thecontainer, and an ex pansion spring arranged to receive the impact ofthe container when the same is actuated by the trigger and to impart aninitial return movement to the container.

3. In an apparatus for the purpose set forth, an oscillatory container,means within the container for closing and breaking an electric circuit,a rock shaft carrying the container, a projection on the rock shaft, atrigger arranged adjacent the container and adapted to be actuated by apassing car wheel, and a pull bar connected to the trigger and adaptedto engage the projection whereby ac tuation of the trigger will rock thecontainer in one direction to close the circuit.

4. In an apparatus for the purpose set forth, an oscillatory container,means within the container for making and breaking an electric circuit,a trigger arranged adjacent the container and adapted to be actuated bya passing car Wheel, a rock shaft carrying the container, a projectionon the rock shaft, a pull bar pivoted to the trigger and normallyengaging the projection, and a second trigger arranged to be operated bya passing car wheel and engaged with the pull bar whereby actuation ofthe second trigger will release the pull bar from the projection toprevent rocking of the container except by a car wheel passing in agiven direction.

5. An apparatus for the purpose set forth comprising a casing, a rockingcontainer mounted in the casing, means within the container for makingand breaking an electric circuit, a trigger mounted within the casingand having a terminal normally projecting above the casing, meanswhereby rocking of the trigger will rock the container to close anelectric circuit, and a trip lever fulcrumed adjacent the end of thecasing and extending over the same to bear upon the projecting end ofthe trigger whereby the passing of a car wheel over the trip lever willactuate the trigger.

6. In an apparatus for the purpose set forth, an oscillatory container,a pull bar, means to be actuated by the pull bar for rockin thecontainer, a trigger connected to the pu 1 bar, and a secondtriggerengaged With the pull bar and controlling the engagement ofthe same withthe container-rocking means whereby the container Will be rocked or Willremain at rest according to the order in which the triggers areactuated.

7 In apparatus for the purpose set forth, an oscillatory container,means Within the container for closing an electric circuit when thecontainer is rocked from normal position, a rock shaft carrying thecontainer, a projection on the rock shaft, a pull bar, a dog carried bythe pull bar and arranged to yield to the projection on the rock shaftwhen moving in one direction and to engage the projection when moving inthe opposite direction, a

trigger connected with the pull bar for actuating the same, and a secondtrigger engaged with the pull bar to hold the dog clear of theprojection or permit its engagement therewith.

I In testimony whereof I afi'ix my signature,

HARRY N. BRANDALL. [n s]

